Polymers containing s-vinylthio alkanols

ABSTRACT

Process for preparing polymers comprising S-vinylthioalkanol as monomer by radical polymerization, the polymerization being carried out in aqueous solution, with the proviso that no N-vinylpyrrolidone as monomer is used for preparing the polymers, and also polymers prepared by such processes. Copolymer consisting of S-vinyl-2-thioethan-1-ol and one or more ethylenically unsaturated monomers selected from the group consisting of acrylic acid, itaconic acid, maleic acid, maleic anhydride, and vinylphosphonic acid. Mixtures, preferably aqueous compositions, comprising polymers or copolymers. Use of polymers, copolymers, or aqueous compositions as concrete plasticizers, wetting agents, in cosmetics, as adhesive constituent, in emulsion polymerization, for metal surface treatment, in coatings applications, in paints, in laundry detergents, in washing detergents, as encapsulating material or as enveloping material.

The present invention relates to processes for preparing polymerscomprising S-vinylthioalkanol as monomer. Further subject matter of theinvention are polymers prepared according to such processes, andspecific copolymers. Subject matter of the invention, furthermore, arethe uses of such polymers and mixtures comprising such polymers.

Further embodiments of the present invention can be found in the claims,the description, and the examples. It is taken as read that the featuresof the subject matter of the invention that have been stated above, andthose still to be illustrated below, may be used not only in thespecific combination indicated in each case, but also in othercombinations, without departing the scope of the invention. Preferredand very preferred, respectively, are also, in particular, thoseembodiments of the present invention in which all features of thesubject matter of the invention have the preferred and very preferreddefinitions, respectively.

Reactive monomers with alkoxylate substituents find application in avery wide variety of technical fields—for example, as concreteplasticizers or as a constituent of varnishes, inks, and paints. Oneknown reactive monomer is 4-hydroxybutyl vinyl ether (HBVE). Radicalhomopolymerization of vinyl ethers leads generally only to oligomers.Water as solvent cannot be used as solvent owing to the highsusceptibility of the vinyl ethers to hydrolysis.

S-Vinylthioalkanols are likewise suitable as reactive monomers withalkoxylate substituents.

Copolymers of S-vinyl-2-thioethan-1-ol with N-vinylpyrrolidone are knownfrom Vorob'eva et al., Vysokomolekulyarne Soedineniya Ser. B, 46,1239-1243 (2004). These copolymers are prepared in bulk or in solvents.Water is among the solvents cited.

Copolymers of S-vinyl-2-thioethan-1-ol withN,N-dimethyl-N,N-diallylammonium chloride are known from Vorob'eva etal., Vysokomolekulyarne Soedineniya Ser. B, 46, 364-368 (2004).

Copolymers of S-vinyl-2-thioethan-1-ol with methyl methacrylate,acrylamide, and acrylonitriles, which are prepared in bulk, are knownfrom DE 2055893 A1.

Copolymers of S-vinyl-2-thioethan-1-ol with styrene and acrylates,prepared in organic solvents, are known from DE 2128681 A1.

Furthermore, Vorob'eva et al., Vysokomolekulyarne Soedineniya Ser. B,45, 700-704 (2003) disclose copolymers with acrylamide, styrene, andmethyl methacrylate, which are prepared in DMSO as solvent.

With the polymers of the prior art, problems are encountered duringtheir preparation. For example, in the course of polymerization orcopolymerization, vinyl ethers do not display particularly highreactivity, and also lead to certain side reactions. Some of the vinylethers, HBVE for example, have only limited hydrolytic stability,especially in an acidic environment.

It was an object of the present invention to provide polymers which donot have the disadvantages identified above. One component of the objectof the invention was the development of reactive monomers withalkoxylate substituents for an efficient polymerization reaction.Another component of the object of the present invention was that ofproviding compounds which, both as monomer and when copolymerized intothe polymer, exhibit an increased hydrolytic stability.

As is evident from the disclosure content of the present invention,these and other objects are achieved by the various embodiments of theinvention, more particularly by processes for preparing polymerscomprising S-vinylthioalkanol as monomer by radical polymerization, thepolymerization being carried out in aqueous solution, with the provisothat no N-vinylpyrrolidone as monomer is used for preparing thepolymers, preferably in an aqueous solution whose solvent mixturecomprises at least 50 weight % of water, more preferably at least 80weight % of water, more particularly 100 weight % of water, based ineach case on the solvent mixture.

S-Vinylthioalkanols are available commercially or may be prepared, forexample, from ethyne (acetylene) and thioalcohols by the Reppe processor by other processes known to the skilled person.

One preferred embodiment of the process of the invention uses, asS-vinylthioalkanol, unsaturated compounds of the general formula (I)

where

-   -   R¹, R², and R³ independently of one another, identically or        differently, are H or CH₃, preferably H, and    -   R⁴ is linear or branched C₁-C₃₀ alkylene, preferably C₂-C₁₀        alkylene, more preferably C₂-C₄ alkylene, more particularly        —CH₂—CH₂—.

Expressions of the form C_(a)-C_(b) refer in the context of thisinvention to chemical compounds or substituents having a defined numberof carbon atoms. The number of carbon atoms may be selected from theentire range from a to h, including a and b; a is at least 1 and b isalways greater than a. Further specification of the chemical compoundsor of the substituents is made using expressions of the form C_(a)-C_(b)V. V here stands for a class of chemical compound or substituent class,such as for alkyl compounds or alkyl substituents.

The collective terms indicated for the various substituents have thefollowing specific definition:

C₁-C₃₀ Alkylene: straight-chain or branched hydrocarbon radicals having1 to 30 carbon atoms, as for example C₁-C₁₀ alkylene or C₁₁-C₂₀alkylene, preferably C₁-C₁₀ alkylene, more particularly methylene,dimethylene, trimethylene, tetramethylene, pentamethylene, orhexamethylene.

With particular preference, the S-vinylthioalkanol is selected from thegroup consisting of S-vinyl-2-thioethan-1-ol, S-vinyl-2-thiopropan-1-ol,S-vinyl-1-thiopropan-2-ol, S-vinyl-2-thiobutan-1-ol,S-vinyl-1-thiobutan-2-ol, S-vinyl-2-thiopentan-1-ol,S-vinyl-1-thiopentan-2-ol, S-vinyl-2-thiocyclohexan-1-ol,S-vinyl-2-thio-(C₁₂-C₂₂)-1-ol, S-vinyl-1-thio-(C₁₂-C₂₂)-2-ol,S-vinyl-1-thiopropane-2,3-diol, S-vinyl-2-thiopropane-1,3-diol,1-phenyl-S-vinyl-1-thioethan-2-ol, and1-phenyl-S-vinyl-2-thioethan-1-ol. The S-vinylthioalkanol is preferablyselected from the group consisting of S-vinyl-2-thioethan-1-ol,S-vinyl-1-thiopropan-2-ol, and S-vinyl-1-thiopropane-2,3-diol; morepreferably the S-vinylthioalkanol is S-vinyl-2-thioethan-1-ol.

Another preferred embodiment of the process of the invention uses atleast one further monomer, different from an S-vinylthioalkanol, forpreparing the polymers, with the proviso, as already mentioned, that noN-vinylpyrrolidone as monomer is used for preparing the polymers.

Preference is given to using as at least one further monomer amonoethylenically unsaturated water-soluble monomer, with the exceptionof vinylpyrrolidone. With particular preference the onemonoethylenically unsaturated water-soluble monomer is selected from thegroup consisting of monoethylenically unsaturated water-soluble monomerhaving one or more acid groups, monoethylenically unsaturatedwater-soluble monomer having one or more ester groups, monoethylenicallyunsaturated water-soluble monomer having one or more amide groups,monoethylenically unsaturated water-soluble monomer having one or moreanhydride groups, monoethylenically unsaturated water-soluble monomerhaving one or more quaternized nitrogen groups, and monoethylenicallyunsaturated water-soluble monomer having one or more heteroaromaticgroups. Especially preferred as monoethylenically unsaturatedwater-soluble monomers are (meth)acrylic acid, maleic acid, maleicanhydride, itaconic acid, vinylphosphonic acid,2-acrylamido-2-methylpropanesulfonic acid, vinylimidazole,tri(m)ethylammonioethyl (meth)acrylate with chloride or methylsulfatecounterion, tri(m)ethylammonioethyl/propyl(meth)acrylamide with chlorideor methylsulfate counterion, methyl-, alkyl-(PEG)x-, (where x is anumber from 200 to 10 000), hydroxyethyl, hydroxypropyl,dimethylaminoethyl or ureido(meth)acrylate, (meth)acrylamide,dimethyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide,methacrylamidoethylethyleneurea, or N-vinylformamide.

A particularly preferred embodiment of the process of the invention usesacrylic acid as monoethylenically unsaturated monomer. Moreparticularly, besides S-vinyl-2-thioethan-1-ol and acrylic acid, nofurther monomers are used for preparing the polymers.

In another embodiment of the process of the invention, the polymersprepared have an upper critical solution temperature (UCST) in water of0 to 99° C., preferably of room temperature (21° C.) to 90° C., moreparticularly of 30 to 80° C.

A further advantage of the process of the invention is that it allowsthe preparation of polymers and copolymers with a readily controllableUCST, more particularly a UCST in water. This applies in particular tocopolymers consisting of acrylic acid and S-vinyl-2-thioethan-1-ol. Thelevel of the UCST here is adjusted via the acrylic acid fraction. Apolymer of S-vinyl-2-thioethan-1-ol/acrylic acid (50/50 molar ratio) hasa UCST in water of about 50° C., a polymer ofS-vinyl-2-thioethan-1-ol/acrylic acid (40/60 molar ratio) has a UCST ofabout 37° C., and a polymer of S-vinyl-2-thioethan-1-ol/acrylic acid(20/80 molar ratio) is completely soluble in water. A homopolymer ofS-vinyl-2-thioethan-1-ol is not soluble in water, but instead, incontrast, is present only as a suspension in water.

The amount of S-vinylthioalkanol employed in the process of theinvention may vary over a wide range according to the application of thepolymer. In the context of the process of the invention, generally from1 to 99 mol % of S-vinylthioalkanol, preferably from 20 to 80 mol %,more preferably from 30 to 70 mol % is used, based on the total amountof monomers.

Correspondingly, in the context of the process of the invention, from 1to 99 mol % of S-vinyl-2-thioethan-1-ol, preferably 20 to 80 mol %, morepreferably 30 to 70 mol %, and from 99 to 1 mol %, preferably 80 to 20mol %, more preferably 70 to 30 mol % of further monomers are used,based on the total amount of monomers. More particularly from 1 to 99mol % of S-vinyl-2-thioethan-1-ol, preferably from 20 to 80 mol %, morepreferably from 30 to 70 mol %, and from 99 to 1 mol %, preferably from80 to 20 mol %, more preferably from 70 to 30 mol % of acrylic acid areused, based on the total amount of monomers.

The invention further provides polymers prepared by the process of theinvention, preferably hydrolysis-stable polymers.

The invention further provides copolymers, preferably hydrolysis-stablecopolymers, consisting of S-vinyl-2-thioethan-1-ol and one or moreethylenically unsaturated monomers selected from the group consisting ofacrylic acid, itaconic acid, maleic acid, maleic anhydride, andvinylphosphonic acid. Preferred copolymers are those consisting ofS-vinyl-2-thioethan-1-ol and acrylic acid.

The invention further provides mixtures, preferably aqueouscompositions, comprising the aforementioned polymers prepared by theprocess of the invention. Preferred are aqueous compositions whichcomprise at least 50 weight % of water, more preferably at least 80weight % of water, more particularly 100 weight % of water, based on thetotal amount of solvent. These mixtures or aqueous compositions have apH of 2 to 10, more preferably a pH of 4 to 8, more particularly a pH of5 to 7.

The invention further provides for the use of the aforementionedpolymers prepared by the process of the invention, or of mixtures,preferably aqueous compositions, comprising such polymers, as concreteplasticizers, wetting agents, in cosmetics, as an adhesive constituent,in emulsion polymerization, for metal surface treatment, in coatingsapplications, in paints, in laundry detergents, in washing detergents,as encapsulating material or as enveloping material.

The present invention provides reactive, hydrolysis-stableS-vinylthioalkanols which can be efficiently reacted tohydrolysis-stable polymers and copolymers. The polymers and copolymersare likewise largely stable toward bases and acids in terms ofhydrolysis on the hydroxyalkyl group. The S-vinylthioalkanols aretherefore suitable, for example, as a hydrolysis-stable substitute forhydroxyalkyl (meth)acrylates.

For example, hydroxyethyl acrylate is about 70% hydrolyzed in water at apH of 13 after 60 minutes; S-vinyl-2-thioethan-1-ol hardly hydrolyzes atall under these basic conditions.

In particular, these monomers are stable in aqueous solution on radicalpolymerization, and the resulting polymers are stable in aqueoussolution on storage. Analogous vinyl ether alcohols, indeed, are nothydrolysis-stable on radical polymerization in water—in the presence ofacids, acetaldehyde and the corresponding diol are formed, but not apolymer.

Moreover, the S-vinylthioalkanols are even hydrolysis-stable oncopolymerization (even with acids such as acrylic acid) or itaconic acidand on storage of the copolymers in aqueous solution.

The invention is elucidated in more detail by the examples, without theexamples restricting the subject matter of the invention.

EXAMPLES Measurement Methods K Values:

The K values were measured in accordance with H. Fikentscher,Cellulose-Chemie, vol. 13, pages 58 to 64 and 71 to 74 (1932) in 1weight % strength aqueous or methanolic solution at 25° C.

GPC Measurement:

The GPC measurements were conducted in N,N-dimethylacetamide (DMAC) withpolymethyl methacrylate (PMMA) (molecular weight distribution of fromM=800 to M=1 820 000) as standard. Columns used:

Columns Diameter Length Separation Cutoff point mm cm material g/molDesignation 8 5 Polyester GRAM preliminary copolymer column 8 30Polyester  100-10 000 GRAM 30 A copolymer 8 30 Polyester 1000-1 000 000GRAM 1000 A copolymer 8 30 Polyester 1000-1 000 000 GRAM 1000 Acopolymer

Example 1 Preparation of S-vinyl-2-thioethan-1-ol/acrylic acid copolymer(ratio 50 mol/50 mol)

A reactor vessel provided with stirrer, temperature monitoring, nitrogeninlet, and a number of feed ports was charged with 58.0 g of deionizedwater, 1.3 g of feed 1, 1.2 g of feed 2, and 1.1 g of feed 3.

Feed 1: 26 g of S-vinyl-2-thioethan-1-ol.

Feed 2: 18 g of acrylic acid and 6 g of deionized water.

Feed 3: 1.32 g of azo initiator(2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, Wako VA-044)and 20 g of deionized water.

The initial charge was gassed with nitrogen for 15 minutes and heated to70° C. under a nitrogen atmosphere. Then the remainder of feed 1 and offeed 2 was added dropwise over the course of 3 hours, and the remainderof feed 3 over the course of 4 hours.

This was followed by stirring at 70° C. for 2 hours. The result was apale yellow, clear polymer solution having a solids content of 29.8% anda K value of 23.2 (1% in methanol).

GPC gave an Mn of 3348 g/mol, an Mw of 6026 g/mol, and PDI (Mw/Mn) of1.8 (calibration plot for PMMA).

Neither residual monomer nor hydrolysis products ofS-vinyl-2-thioethan-1-ol were detectable by ¹H NMR spectroscopy. Inorder to detect potential hydrolysis products, ¹H NMR standard-additiontests were additionally conducted with 2-thioethan-1-ol and also withethylene glycol.

The upper critical solution temperature (UCST) of the copolymer in waterwas about 50° C.

Example 2 Preparation of S-vinyl-2-thioethan-1-ol/acrylic acid copolymer(ratio 40 mol/60 mol)

A reactor vessel provided with stirrer, temperature monitoring, nitrogeninlet, and a number of feed ports was charged with 63.8 g of deionizedwater, 1.5 g of feed 1, 2.5 g of feed 2, and 1.6 g of feed 3.

Feed 1: 29.2 g of S-vinyl-2-thioethan-1-ol.

Feed 2: 30.3 g of acrylic acid and 20.0 g of deionized water.

Feed 3: 1.8 g of Wako VA-044 and 30 g of deionized water.

The initial charge was gassed with nitrogen for 15 minutes and heated to70° C. under a nitrogen atmosphere. Than the remainder of feed 1 and offeed 2 was added dropwise over the course of 3 hours, and the remainderof feed 3 over the course of 4 hours.

This was followed by stirring at 70° C. for 2 hours. The result was apale yellow, clear polymer solution having a solids content of 27.6% anda K value of 24.7 (1% in methanol).

Neither residual monomer nor hydrolysis products ofS-vinyl-2-thioethan-1-ol were detectable by ¹H NMR spectroscopy. Inorder to detect potential hydrolysis products, ¹H NMR standard-additiontests were additionally conducted with 2-thioethan-1-ol and also withethylene glycol.

The upper critical solution temperature (UCST) of the copolymer in waterwas about 37° C.

Example 3 Preparation of S-vinyl-2-thioethan-1-ol homopolymer

A reactor vessel provided with stirrer, temperature monitoring, nitrogeninlet, and a number of feed ports was charged with 29.8 g of deionizedwater, 30.0 g of ethanol, 2.0 g of feed 1 and 1.1 g of feed 2.

Feed 1: 41.7 g of S-vinyl-2-thioethan-1-ol.

Feed 2: 1.25 g of Wako VA-044 and 20 g of deionized water.

Feed 3: 0.83 g of Wako VA-044 and 13.33 g of water.

The initial charge was gassed with nitrogen for 15 minutes and heated to70° C. under a nitrogen atmosphere. Then the remainder of feed 1 wasadded dropwise over the course of 3 hours, and the remainder of feed 2over the course of 4 hours. This was followed by stirring at 70° C. for2 hours. Subsequently feed 3 was added dropwise over the course of 45minutes and stirring took place at 70° C. for 2 hours.

The result was a pale yellow, clear polymer solution having a solidscontent of 28.3% and a K value of 23.3 (1% in methanol).

The residual monomer content was about 2 mol %, based on the totalamount of monomer employed. GPC gave an Mn of 6718 g/mol, an Mw of 16680 g/mol, and PDI 2.5 (calibration plot for PMMA).

Example 4 Preparation of S-vinyl-2-thioethan-1-ol/acrylic acid copolymer(ratio 10 mol/90 mol)

A reactor vessel provided with stirrer, temperature monitoring, nitrogeninlet, and a number of feed ports was charged with 73.6 g of deionizedwater, 6.0 g of feed 1 and 2.25 g of feed 2.

Feed 1: 77.82 g of acrylic acid, 12.50 g of S-vinyl-2-thioethan-1-ol,and 30.0 g of deionized water.

Feed 2: 5.42 g of azo initiator (2,2′-azobis(2-methylpropionamidine)dihydrochloride, Wako V-50) and 40.0 g of deionized water.

The initial charge was gassed with nitrogen for 15 minutes and heated to88° C. under a nitrogen atmosphere. Then the remainder of feed 1 wasadded dropwise over the course of 3 hours, and the remainder of feed 2over the course of 4 hours. This was followed by stirring at 88° C. for2 hours.

The result was a pale yellow, clear polymer solution having a solidscontent of 40.6% and a K value of 12.7 (1% in water).

Neither residual monomer nor hydrolysis products ofS-vinyl-2-thioethan-1-ol were detectable by ¹H NMR spectroscopy. Inorder to detect potential hydrolysis products, ¹H NMR standard-additiontests were additionally conducted with 2-thioethan-1-ol and also withethylene glycol.

Example 5 Preparation of S-vinyl-2-thioethan-1-ol/acrylic acid copolymer(ratio 20 mol/80 mol)

A reactor vessel provided with stirrer, temperature monitoring, nitrogeninlet, and a number of feed ports was charged with 79.75 g of deionizedwater, 6.2 g of feed 1 and 2.3 g of feed 2.

Feed 1: 69.18 g of acrylic acid, 25.0 g of S-vinyl-2-thioethan-1-ol, and30.0 g of deionized water.

Feed 2: 5.65 g of Wako V-50 and 40.0 g of deionized water.

The initial charge was gassed with nitrogen for 15 minutes and heated to88° C. under a nitrogen atmosphere. Then the remainder of feed 1 wasadded dropwise over the course of 3 hours, and the remainder of feed 2over the course of 4 hours. This was followed by stirring at 88° C. for2 hours.

The result was a pale yellow, clear polymer solution having a solidscontent of 39.2% and a K value of 10.5 (1% in water).

Neither residual monomer nor hydrolysis products ofS-vinyl-2-thioethan-1-ol were detectable by ¹H NMR spectroscopy. Inorder to detect potential hydrolysis products, ¹H NMR standard-additiontests were additionally conducted with 2-thioethan-1-ol and also withethylene glycol.

Example 6 Preparation of S-vinyl-2-thioethan-1-ol/acrylic acid/itaconicacid/vinylphosphonic acid copolymer ratio 5 mol/55 mol/30 mol/10 mol)

A reactor vessel provided with stirrer, temperature monitoring, nitrogeninlet, and a number of feed ports was charged with 42.67 g of deionizedwater, 9.32 g of vinylphosphonic acid (95% strength), and 32.0 g ofitaconic acid. The initial charge was gassed with nitrogen for 15minutes and heated to 98° C. under a nitrogen atmosphere. Then 32.5 g ofacrylic acid, 4.3 g of S-vinyl-2-thioethan-1-ol, and 30.0 g of deionizedwater were added dropwise over the course of 5 hours, and 3.1 g of WakoV-50 and 48.0 g of deionized water over the course of 6 hours. This wasfollowed by stirring at 98° C. for 2 hours.

This gave a clear yellow polymer solution having a solids content of39.9% and a K value of 13.0 (1% in water). 2.9 mol % of vinylphosphonicacid, based on the total amount of vinylphosphonic acid employed, wasdetectable in the ¹H and ³¹P NMR spectrum.

Example 7 Application Examples

The copolymers from examples 4 and 5 were used for coating test panelsof hot-dip-galvanized steel (Gardobond OE HDG 3; 105×190 m).

As a pretreatment, the test panels were immersed for 30 seconds in amildly alkaline cleaning agent solution (Surtech 133 from Surtech) andthen rinsed off immediately with fully demineralized water andsubsequently dried using nitrogen. The clean panels were immersed for 1second in a 25 weight % strength aqueous solution of the copolymer,squeezed off with a system of rollers, and dried in a forced-air dryingcabinet at 160° C. for 12 seconds. In the course of this operation, thepeak metal temperature (PMT) did not exceed 50° C.

The resulting test panels were investigated for their corrosionresistance in a DIN EN ISO 9227 salt spray test.

Polymer corroded area after salt spray test: No coating 100% (fullycorroded) AA/S-Vinyl-2-thioethan-1-ol 90/10 about 30%AA/S-Vinyl-2-thioethan-1-ol 80/20 about 10%

The data demonstrate the passivating effect through the copolymers ofthe invention.

1-16. (canceled) 17: A process for preparing a polymer comprising aS-vinylthioalkanol as monomer by radical polymerization, which comprisescarrying out the polymerization in aqueous solution, with the provisothat no N-vinylpyrrolidone is used as monomer for preparing the polymer,and wherein at least one further monomer, different from anS-vinylthioalkanol, is used, the further monomer being amonoethylenically unsaturated water-soluble monomer, with the exceptionof vinylpyrrolidone. 18: The process according to claim 17, wherein, asa S-vinylthioalkanol, unsaturated compounds of the general formula (I)are used

where R¹, R², and R³ independently of one another, identically, ordifferently, are H or CH₃ and R⁴ is linear or branched C₁-C₃₀ alkylene.19: The process according to claim 17, wherein the S-vinylthioalkanol isselected from the group consisting of S-vinyl-2-thioethan-1-ol,S-vinyl-2-thiopropan-1-ol, S-vinyl-1-thiopropan-2-ol,S-vinyl-2-thiobutan-1-ol, S-vinyl-1-thiobutan-2-ol,S-vinyl-2-thiopentan-1-ol, S-vinyl-1-thiopentan-2-ol,S-vinyl-2-thiocyclohexan-1-ol, S-vinyl-2-thio-(C₁₂-C₂₂)-1-ol,S-vinyl-1-thio-(C₁₂-C₂₂)-2-ol, S-vinyl-1-thiopropane-2,3-diol,S-vinyl-2-thiopropane-1,3-di of, 1-phenyl-S-vinyl-1-thioethan-2-ol, and1-phenyl-S-vinyl-2-thioethan-1-ol. 20: The process according to claim19, wherein at least one further monomer is selected from the groupconsisting of monoethylenically unsaturated water-soluble monomer havingone or more acid groups, monoethylenically unsaturated water-solublemonomer having one or more ester groups, monoethylenically unsaturatedwater-soluble monomer having one or more amide groups, monoethylenicallyunsaturated water-soluble monomer having one or more anhydride groups,monoethylenically unsaturated water-soluble monomer having one or morequaternized nitrogen groups, and monoethylenically unsaturatedwater-soluble monomer having one or more heteroaromatic groups. 21: Theprocess according to claim 20, wherein, as at least onemonoethylenically unsaturated monomer, acrylic acid is used. 22: Theprocess according to claim 21, wherein besides S-vinyl-2-thioethan-1-oland acrylic acid no further monomers are used. 23: The process accordingto claim 17, wherein the resultant polymer has an upper criticalsolution temperature in water of 0 to 99° C. 24: The process accordingto claim 17, wherein from 1 to 99 mol % of S-vinylthioalkanol is used,based on the total amount of monomers. 25: The process according toclaim 19, wherein from 1 to 99 mol % of S-vinyl-2-thioethan-1-ol andfrom 99 to 1 mol % of further monomers are used, based on the totalamount of monomers. 26: The process according to claim 22, wherein from1 to 99 mol % of S-vinyl-2-thioethan-1-ol and from 99 to 1 mol % ofacrylic acid is used, based on the total amount of monomers. 27: Apolymer comprising S-vinylthioalkanol as monomer and at least onefurther monomer, different from an S-vinylthioalkanol, the furthermonomer being a monoethylenically unsaturated water-soluble monomer,with the exception of vinylpyrrolidone, prepared by a process accordingto claim
 17. 28: A copolymer comprising S-vinyl-2-thioethan-1-ol and oneor more ethylenically unsaturated monomers selected from the groupconsisting of acrylic acid, itaconic acid, maleic acid, maleicanhydride, and vinylphosphonic acid. 29: A mixture, comprising a polymeraccording to claim
 27. 30: A mixture, comprising a polymer according toclaim
 28. 31: An aqueous composition, comprising a polymer according toclaim
 27. 32: An aqueous composition, comprising a polymer according toclaim
 28. 33: A method of enhancing hydrolytic stability of acomposition, comprising adding a polymer according to claim 27 to acomposition, thereby enhancing the hydrolytic stability of thecomposition. 34: A method according to claim 33, wherein the compositionis at least one member selected from the group consisting of concrete, awetting agent, a cosmetic, an adhesive composition, an emulsionpolymerization system, a metal surface treating agent, a coatingcomposition, a paint, a laundry detergent, a washing detergent, anencapsulating material, and an enveloping material. 35: A methodaccording to claim 33, wherein said polymer reduces corrosion in saidcomposition. 36: A method of enhancing hydrolytic stability of acomposition, comprising adding a polymer according to claim 28 to acomposition, thereby enhancing the hydrolytic stability of thecomposition. 37: A method according to claim 36, wherein the compositionis at least one member selected from the group consisting of concrete, awetting agent, a cosmetic, an adhesive composition, an emulsionpolymerization system, a metal surface treating agent, a coatingcomposition, a paint, a laundry detergent, a washing detergent, anencapsulating material, and an enveloping material. 38: A methodaccording to claim 36, wherein said polymer reduces corrosion in saidcomposition.